Probabilistic Constellation Shaping for Optical Fiber Communications

Junho Cho, Peter Winzer
2019 Journal of Lightwave Technology  
We review probabilistic constellation shaping (PCS), which has been a key enabler for several recent record-setting optical fiber communications experiments. PCS provides both finegrained rate adaptability and energy efficiency (sensitivity) gains. We discuss the reasons for the fundamentally better performance of PCS over other constellation shaping techniques that also achieve rate adaptability, such as time-division hybrid modulation, and examine in detail the impact of sub-optimum shaping
more » ... d forward error correction (FEC) on PCS systems. As performance metrics for systems with PCS, we compare information-theoretic measures such as mutual information (MI), generalized MI (GMI), and normalized GMI, which enable optimization and quantification of the information rate (IR) that can be achieved by PCS and FEC. We derive the optimal parameters of PCS and FEC that maximize the IR for both ideal and non-ideal PCS and FEC. To avoid plausible pitfalls in practice, we carefully revisit key assumptions that are typically made for ideal PCS and FEC systems. Index Terms-Modulation, optical fiber communication, probabilistic constellation shaping, quadrature amplitude modulation.
doi:10.1109/jlt.2019.2898855 fatcat:imvzsmxndrdvxou6uhbb3mqxmm